I was wondering if anyone knows a simple way to extract a piece of a song from an mp3 file? I want to create something like a networked music quiz game which selects a song from a players local music library, extracts 10-30 seconds from it and asks the other players about something from the ID3 tags (which album, what artist/band, song title, year, ..). It could either create a new smaller mp3 file or just a wav file, I don't really care. I'm looking for a library or a commandline tool which can do this. I've tried googling, but didn't find anything, except gui tools or tutorials on how to extract pieces using something like audacity. So, any ideas?

I realise you want a technical answer and I am posting a legal answer. Sorry about that but it's one of the hazards of posting in a public forum.

This is a personal project for me and my friends, using legal mp3s.

You mean you/your friends wrote all the music that is going to be used and you own the copyright on it? Otherwise you're almost certainly on shaky ground using the term "legal mp3s". Creating a quiz app that uses parts of other peoples copyright works would almost certainly constitute copyright infringement - especially given that the express purpose is for people to be able to identify the music being used.

I realise you want a technical answer and I am posting a legal answer. Sorry about that but it's one of the hazards of posting in a public forum.

This is a personal project for me and my friends, using legal mp3s.

You mean you/your friends wrote all the music that is going to be used and you own the copyright on it? Otherwise you're almost certainly on shaky ground using the term "legal mp3s". Creating a quiz app that uses parts of other peoples copyright works would almost certainly constitute copyright infringement - especially given that the express purpose is for people to be able to identify the music being used.

Think about it as something for a lan party or whatever. Instead of me standing next to a stereo and pressing play/pause and everyone writing the answers on sheets, it's done by this game. Anyone, I solved it using mp3splt.

Think about it as something for a lan party or whatever. Instead of me standing next to a stereo and pressing play/pause and everyone writing the answers on sheets, it's done by this game. Anyone, I solved it using mp3splt.

I'm afraid from a legal stand point your analogy is flawed, because you aren't a piece of software or a machine specifically designed in such a way that it can only function (in a meaningful way) with the use of (other people's) copyright material.

It's a quiz program requiring people to identify a tune, the composer, performer or some other details relating to that music. For players to identify these details, the music used must be something that would be known to a significant percentage of users. It would be pointless writing your own music, and then asking people about it, as they wouldn't have heard it before. Therefore, by default, the software requires the use of copyright music (unless you are planning to track down recordings that are so old they are out of copyright). Legally your software would be no different from something like Rockband or Guitar Hero. The publishers of both of those products could have commissioned original music but they knew that this would not have had anything like the appeal that well known music track have - hence they licensed known music. Likewise the success of your product requires the use of known music so, unless you own the copyright to the Beatles back catalogue, that means the use of someone else's copyright material. A court would have no hesitation in ruling that your product infringes copyright.

Of course this is just the legal position. If, as you claimed in you first post, this product is just for the personal use of you and a few friends, then there won't be a problem. The copyright owners (or their representatives/lawyers) will never hear about your software and thus will never be able to take action. Obviously if you were to distribute the software and it became successful the protection afforded you by their ignorance would vanish.

I was wondering if anyone knows a simple way to extract a piece of a song from an mp3 file? I want to create something like a networked music quiz game which selects a song from a players local music library, extracts 10-30 seconds from it and asks the other players about something from the ID3 tags (which album, what artist/band, song title, year, ..). It could either create a new smaller mp3 file or just a wav file, I don't really care. I'm looking for a library or a commandline tool which can do this. I've tried googling, but didn't find anything, except gui tools or tutorials on how to extract pieces using something like audacity. So, any ideas?

This is a personal project for me and my friends, using legal mp3s.

There is a very serious legal issue here. Obscure has pointed it out.

If you are attempting this for any kind of public release, you will need to sit down face-to-face with a real IP lawyer and figure out how to solve those serious legal issues. It does not matter if money is involved or not, or even if you are just giving it out to a few friends. If you attempt to distribute it AT ALL you may discover yourself facing the combined wrath of several global corporations. Even giving it away for free to a few close friends may be enough for these companies to sue and potentially win and force you into bankruptcy.

Software development as a hobby is fine. But any distribution of goods (even to close friends) will automatically place you into a category of a commercial venture in the eyes of the law. Proceed with caution.

And as for a solution, your own post seems to propose them:

* You want to extract ID3 tags. There are many tools out there, the simple search extract id3 tags gave me a list of systems that do exactly that.* You want to play a segment of audio. There is no need to recode or extract the audio, simply use your media player to seek to a time index and play back the audio for a few seconds. This is probably the most safe option from a legal standpoint since you are doing nothing but replaying a user-specified segment of the user-specified audio file at the user's request, without making any copies or extracting clips.* If you do want to extract audio segments you will need to identify the audio segments to extract anyway. Tools like Audacity will help you do both of them. Why is this not a solution for you?* If you have identified the audio segments to extract but for some reason cannot use a reasonable editor, then you simply decode the audio using your built-in audio player and store it to a buffer, which can be replayed at your convenience.

I'm not distributing music. The program just picks a random song and picks a random 20 second segment from that song which it plays, and then lets the user guess something from the songs ID3 tags.

The program is hardcoded for me and my home, and is actually distributed over 4 computers. One has the database, one the music files, one the questions and one which plays the music segment. Instead of sending the entire mp3 to that computer, the small segment is sent instead.

So there's no distribution of anything anywhere except over my LAN.

I got everything to work at last, and it's LOTS of fun actually, but insanely hard. I'm still trying to improve it's abilities to take answers that doesn't exactly match the tag data using things like Levenstein distance and soundex, but it's fairly hard.